If x is the least positive integer satisfying 97 ≡ x(mod 5), then $x^2-1$ is equal to:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 3
$97 \equiv x \ (\text{mod } 5)$
$97 = 5 \times 19 + 2 \Rightarrow x = 2$
$x^2 - 1 = 2^2 - 1 = 4 - 1 = 3$
$x^2 - 1 = 3$